Question

984. String Without AAA or BBB

中文文档

Description

Given two integers a and b, return any string s such that:

• s has length a + b and contains exactly a 'a' letters, and exactly b 'b' letters,
• The substring 'aaa' does not occur in s, and
• The substring 'bbb' does not occur in s.

 

Example 1:

Input: a = 1, b = 2
Output: "abb"
Explanation: "abb", "bab" and "bba" are all correct answers.

Example 2:

Input: a = 4, b = 1
Output: "aabaa"

 

Constraints:

• 0 <= a, b <= 100
• It is guaranteed such an s exists for the given a and b.

Solutions

Solution 1

class Solution:
  def strWithout3a3b(self, a: int, b: int) -> str:
    ans = []
    while a and b:
      if a > b:
        ans.append('aab')
        a, b = a - 2, b - 1
      elif a < b:
        ans.append('bba')
        a, b = a - 1, b - 2
      else:
        ans.append('ab')
        a, b = a - 1, b - 1
    if a:
      ans.append('a' * a)
    if b:
      ans.append('b' * b)
    return ''.join(ans)

class Solution {
  public String strWithout3a3b(int a, int b) {
    StringBuilder ans = new StringBuilder();
    while (a > 0 && b > 0) {
      if (a > b) {
        ans.append("aab");
        a -= 2;
        b -= 1;
      } else if (a < b) {
        ans.append("bba");
        a -= 1;
        b -= 2;
      } else {
        ans.append("ab");
        --a;
        --b;
      }
    }
    if (a > 0) {
      ans.append("a".repeat(a));
    }
    if (b > 0) {
      ans.append("b".repeat(b));
    }
    return ans.toString();
  }
}

class Solution {
public:
  string strWithout3a3b(int a, int b) {
    string ans;
    while (a && b) {
      if (a > b) {
        ans += "aab";
        a -= 2;
        b -= 1;
      } else if (a < b) {
        ans += "bba";
        a -= 1;
        b -= 2;
      } else {
        ans += "ab";
        --a;
        --b;
      }
    }
    if (a) ans += string(a, 'a');
    if (b) ans += string(b, 'b');
    return ans;
  }
};

func strWithout3a3b(a int, b int) string {
  var ans strings.Builder
  for a > 0 && b > 0 {
    if a > b {
      ans.WriteString("aab")
      a -= 2
      b -= 1
    } else if a < b {
      ans.WriteString("bba")
      a -= 1
      b -= 2
    } else {
      ans.WriteString("ab")
      a--
      b--
    }
  }
  if a > 0 {
    ans.WriteString(strings.Repeat("a", a))
  }
  if b > 0 {
    ans.WriteString(strings.Repeat("b", b))
  }
  return ans.String()
}